The music recording industry went through a transition to digital audio recording methods in the 1980s. Most major recording studios adopted early-generation digital recording equipment replacing the then thirty-year-old analog tape recording equipment. The product of the technology shift was the now ubiquitous compact disc recording or CD which rapidly replaced the long-playing analog disk now as the vinyl LP.
The initial generation of digital audio processing equipment is now recognized as deficient in audio accuracy in many ways and the quality of audio recordings suffered as a result. Hence, many audiophiles rejected the sound quality of CDs and remained users of the vinyl LP and its associated playback means. In the last decade, the sales of vinyl LPs has seen a strong growth with sales increasing more than 50% year-over-year.
The typically mature audiophile continues to be a major purchaser of both new and used LPs and, in the last decade or so, has been joined by a much younger generation who are discovering the refined audio quality of the vinyl LP recording. Undoubtedly, the fascination of the old-fashioned technology and associated equipment attracts many new users but the audio industry continues to innovate and produced better quality playback equipment at all price points of the consumer electronics industry.
The old-generation, master recording analog magnetic tapes are aging, missing or were destroyed in several notable fires in storage facilities. The analog magnetic tape masters still on the shelves of the record companies after many decades are aging and demagnetizing. Further loss of reference recordings occurred because many popular artist's analog tape recordings from the period of the late 1950's to the mid-1980's, when the digital recording transition began, were transferred to digital tape and the original analog recordings were actually discarded.
The last many decades have left the archive libraries of master tapes of great music with poor quality audio recordings of some very important musicians and performances. This gap spans the period of around 1985 to as recently as 2010. When a music label or service wishes to re-release a recording from the past, if the master tape is missing, the company will use a phonograph recording and record it digitally. This industry technique is known to the skilled person as a “needle drop.”
In order to obtain a usable recording from a phonograph record one needs to apply many engineering best practices including the use of high-end turntables and high-quality audio electronics. Most phonograph players use single tonearms that trace an arc across the surface of the record as the needle follows the groove. Unfortunately, the record master disk was cut on a lathe with a cutting head driven on a worm screw straight across the surface of the disk. This mismatch of geometries of a straight line versus an arc results in measurable playback distortion.
Various attempts to minimize said tracking distortion of phonograph players have been proposed. The most obvious solution is to use a so-called linear tonearm where instead of pivoting in an arc at the end of a fixed shaft, the cartridge is transported along a direct radial path following the straight track of the original cutting head. However, the record master cutting head was pushed across the master record on a turning worm screw shaft while cutting the master whereas said linear playback solutions introduce new sources of distortion and noise due to side-loading forces on the stylus and cantilever resulting from the force exerted to pull the entire playback mechanism along the record from outer to inner groove.
This invention addresses the need for much more accurate playback of phonograph records which is of particular interest to recording studios that need to recover previous made recordings with quality close to the original master tapes that made the phonograph recording.